ZIP / postal code format

What this rule does

A malformed ZIP is almost always a typo, and a ZIP typo is enough to route a package to the wrong sorting facility. The rule knows each covered country's format and flags codes that can't be right before they cost you a redelivery.

What it catches

• ZIP 1234 on a US address (US ZIPs have five digits)
• K1A 0B on a Canadian address (Canadian codes are six characters, like K1A 0B1)

Formats are checked for the US, Canada, the UK, Germany, the Netherlands, France, and Australia. Addresses in other countries pass without a format check. We'd rather let an unusual format through than block a real buyer over a rule we can't be sure about.

What your buyer sees

Set to Block at checkout

Your buyer sees the message right at the address field, inside Shopify's own checkout, before payment. They fix the address and pay. The check runs inside checkout itself, so it adds no waiting time and nothing changes in your theme. Our default message:

You can replace it with your own wording in the rule's settings.

Set to Warn after purchase

The sale completes normally. On the order confirmation page we ask the buyer to double-check the address, and when we have a verified fix they can apply it with one tap. Orders with unresolved address problems are tagged address-unverified in your admin so you can catch them before fulfillment. This mode works with every payment method, including Apple Pay and Google Pay express checkouts.

If a check can't run for any reason, the order goes through untouched. We never hold up a sale on our own uptime.

Set it up

Open Address Verifier in your Shopify admin, go to Settings, and pick ZIP / postal code format. Choose Off, Warn after purchase, or Block at checkout, write your own checkout message if you want one, and save. Changes are live on your next checkout. No deploy, no theme edit.

New installs start with this rule set to Warn after purchase. It catches real mistakes without turning away a single sale.